Method of cleaning, method of manufacturing semiconductor device, substrate processing apparatus, and recording medium

ABSTRACT

There is provided a technique of cleaning an inside of a process container, including: (a) removing substances adhered in a process container set at a first temperature by supplying a first gas at a first flow rate into the process container and exhausting the inside of the process container; (b) physically desorbing and removing residual fluorine in the process container set at a second temperature by supplying a second gas at a second flow rate into the process container and exhausting the inside of the process container; and (c) chemically desorbing and removing residual fluorine in the process container set at a third temperature by supplying a third gas at a third flow rate into the process container and exhausting the inside of the process container.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2018-178942, filed on Sep. 25, 2018, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method of cleaning, a method ofmanufacturing a semiconductor device, a substrate processing apparatus,and a recording medium.

BACKGROUND

As a process of manufacturing a semiconductor device, a process ofcleaning the inside of a process container by supplying a gas includinga fluorine-based gas into the process container after performingsubstrate processing for forming a film over a substrate is oftencarried out. In this case, when the next substrate processing isperformed in the cleaned process container, the productivity may bedeteriorated.

SUMMARY

Some embodiments of the present disclosure provide a technique capableof performing the next substrate processing without deteriorating theproductivity after cleaning the inside of a process container.

According to one or more embodiments of the present disclosure, there isprovided a technique of cleaning an inside of a process container,including: (a) removing substances adhered in a process container set ata first temperature after performing a process on a substrate bysupplying a first gas including a fluorine-based gas at a first flowrate into the process container and exhausting the inside of the processcontainer; (b) physically desorbing and removing residual fluorine inthe process container set at a second temperature higher than the firsttemperature after performing (a) by supplying a second gas, which doesnot react chemically with fluorine under the second temperature, at asecond flow rate higher than the first flow rate and a third flow rateinto the process container and exhausting the inside of the processcontainer; and (c) chemically desorbing and removing residual fluorinein the process container set at a third temperature higher than thefirst temperature after performing (a) by supplying a third gas, whichreacts chemically with fluorine under the third temperature, at thethird flow rate into the process container and exhausting the inside ofthe process container.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration view of a vertical process furnaceof a substrate processing apparatus suitably used in embodiments of thepresent disclosure, in which a portion of the process furnace is shownin a vertical cross section.

FIG. 2 is a schematic configuration view of the vertical process furnaceof the substrate processing apparatus suitably used in the embodimentsof the present disclosure, in which a portion of the process furnace isshown in a cross section taken along line A-A in FIG. 1 .

FIG. 3 is a schematic configuration diagram of a controller of tiresubstrate processing apparatus suitably used in the embodiments of thepresent disclosure, in which a control system of the controller is shownin a block diagram.

FIG. 4 is a diagram showing a sequence of cleaning processing accordingto one or more embodiments of the present disclosure.

FIG. 5 is a view showing the film thickness of a film formed over asubstrate every batch processing (BAT) when repeatedly performingsubstrate processing, that is, the BAT for simultaneously processing aplurality of substrates (wafers), after cleaning the inside of a processcontainer in an Embodiment Example and a Comparative Example.

FIG. 6 is a view illustrating a period until substrate processing for aproduct substrate, that is, batch processing (product BAT) forsimultaneously processing a plurality of product substrates (productwafers) is started after cleaning the inside of a process container inthe Embodiment Example and the Comparative Example.

DETAILED DESCRIPTION One or More Embodiments of the Present Disclosure

One or more embodiments of the present disclosure will be now describedwith reference to FIGS. 1 to 4 .

(1) Configuration of Substrate Processing Apparatus

As illustrated in FIG. 1 , a process furnace 202 includes a heater 207as a heating mechanism (a temperature adjustment part). The heater 207has a cylindrical shape and is supported by a support plate so as to bevertically installed. The heater 207 also functions as an activationmechanism (an excitation part) configured to thermally activate (excite)a gas.

A reaction tube 203 is disposed inside the heater 207 to be concentricwith the heater 207. The reaction tube 203 is made of, for example, aheat resistant material such as quartz (SiO₂), silicon carbide (SiC) orthe like, and has a cylindrical shape with its upper end closed and itslower end opened. A manifold 209 is disposed to be concentric with thereaction tube 203 under the reaction tube 203. The manifold 209 is madeof, for example, a metal material such as stainless steel (SUS: SteelUse Stainless) or the like, and has a cylindrical shape with both of itsupper and lower ends opened. The upper end portion of the manifold 209engages with the lower end portion of the reaction tube 203 so as tosupport the reaction tube 203. An O-ring 220 a serving as a seal memberis installed between the manifold 209 and the reaction tube 203. Similarto the heater 207, the reaction tube 203 is vertically installed. Aprocess container (reaction container) mainly includes the reaction tube203 and the manifold 209. A process chamber 201 is formed in a hollowcylindrical portion of the process container. The process chamber 201 isconfigured to accommodate a plurality of wafers 200 as substrates.Processing on the wafers 200 is performed in the process chamber 201.

Nozzles 249 a and 249 b as first and second supply parts are installedin the process chamber 201 so as to penetrate through a sidewall of themanifold 209. The nozzles 249 a and 249 b are also called first andsecond nozzles. The nozzles 249 a and 249 b are made of, for example, aheat resistant material such as quartz, SiC or the like. Gas supplypipes 232 a and 232 b are connected to the nozzles 249 a and 249 b,respectively. The nozzles 249 a and 249 b are different from each other.

Mass flow controllers (MFCs) 241 a and 241 b, which are flow ratecontrollers (flow rate control parts), and valves 243 a and 243 b, whichare opening-closing valves, are installed in the gas supply pipes 232 aand 232 b, respectively, sequentially from the upstream side of gasflow-. Gas supply pipes 232 c and 232 e are connected to the gas supplypipe 232 a at the downstream side of the valve 243 a. Gas supply pipes232 d and 232 f are connected to the gas supply pipe 232 b at thedownstream side of the valve 243 b. MFCs 241 c to 241 f and valves 243 cto 243 f are installed in the gas supply pipes 232 c to 232 f,respectively, sequentially from the upstream side of gas flow. Hie gassupply pipes 232 c to 232 f are made of, for example, a metal materialsuch as stainless steel (SUS) or the like.

As illustrated in FIG. 2 , each of the nozzles 249 a and 249 b isdisposed in an annular space (in a plane view) between an inner wall ofthe reaction tube 203 and the wafers 200 so as to extend upward along anarrangement direction of the wafers 200 from a lower portion of theinner wall of the reaction tube 203 to an upper portion thereof.Specifically, each of the nozzles 249 a and 249 b is installed in aregion horizontally surrounding a wafer arrangement region in which thewafers 200 are arranged at a lateral side of the wafer arrangementregion, along the wafer arrangement region. Gas supply holes 250 a and250 b for supplying a gas are formed on side surfaces of the nozzles 249a and 249 b, respectively. The gas supply holes 250 a and 250 b allowthe gas to be supplied toward the wafers 200. A plurality of gas supplyholes 250 a and 250 b may be formed from a lower portion of the reactiontube 203 to an upper portion thereof.

A precursor (precursor gas), for example, a halosilane-based gascontaining Si, which is a predetermined element (main element)constituting a film, and a halogen element, is supplied from the gassupply pipe 232 a into the process chamber 201 via the MFC 241 a, thevalve 243 a, and the nozzle 249 a. The precursor gas refers to a gaseousprecursor, for example, a precursor which remains in a gas state at roomtemperature and atmospheric pressure, or gas obtained by vaporizing aprecursor which remains in a liquid state at room temperature andatmospheric pressure. The halosilane refers to silane including ahalogen group. The halogen group includes a chloro group, a fluorogroup, a bromo group, an iodo group, and the like. That is, the halogengroup includes halogen elements such as chlorine (Cl), fluorine (F),bromine (Br), iodine (I), and the like. An example of thehalosilane-based gas may include a precursor gas containing Si and Cl,that is, a chlorosilane-based gas. The chlorosilane-based gas acts as aSi source. An example of the chlorosilane-based gas may include ahexachlorodisilane (Si₂Cl₆, abbreviation: HCDS) gas. The HCDS gas is agas containing an element (Si) which becomes solid alone under a processcondition to be described below, that is, a gas capable of depositing afilm alone under the process condition to be described below.

A reactant (reaction gas), for example, a hydrogen nitride-based gas,which is a nitrogen (N)-containing gas, is supplied from the gas supplypipe 232 b into the process chamber 201 via the MFC 241 b, the valve 243b, and the nozzle 249 b. Tire hydrogen nitride-based gas acts as anitriding gas, that is, 3 n N source. An example of the hydrogennitride-based gas may include an ammonia (NH₃) gas. The NH₃ gas is a gascontaining an element (N) which does not become solid alone under theprocess condition to be described below, that is, a gas incapable ofdepositing a film alone under the process condition to be describedbelow.

A fluorine-based gas is supplied from the gas supply pipe 232 c into theprocess chamber 201 via the MFC 241 c, the valve 243 c, the gas supplypipe 232 a, and the nozzle 249 a. An example of the fluorine-based gasmay include a fluorine (F₂) gas.

A nitrogen oxide-based gas is supplied from the gas supply pipe 232 dinto the process chamber 201 via the MFC, 241 d, the valve 243 d, thegas supply pipe 232 b, and the nozzle 249 b. The nitrogen oxide-basedgas alone does not show a cleaning effect, but reacts with thefluorine-based gas to generate active species such as fluorine radicals,a nitrosyl fluoride compound and the like and thus act to improve thecleaning effect of the fluorine-based gas. An example of the nitrogenoxide-based gas may include a nitrogen monoxide (NO) gas.

An inert gas, for example, a nitrogen (N₂) gas, is supplied from the gassupply pipes 232 e and 232 f into the process chamber 201 via the MFCs241 e and 241 f, the valves 243 e and 243 f, the gas supply pipes 232 aand 232 b, and the nozzles 249 a and 249 b, respectively. The N₂ gasacts as a purge gas, a carrier gas, a dilution gas, or the like.

A precursor supply system mainly includes the gas supply pipe 232 a, theMFC 241 a, and the valve 243 a. A reactant supply system mainly includesthe gas supply pipe 232 b, the MFC 241 b, and the valve 243 b. Afluorine-based gas supply system mainly includes the gas supply pipe 232c, the MFC 241 e, and the valve 243 c. A nitrogen oxide-based gas supplysystem mainly includes the gas supply pipe 232 d, the MFC 241 d, and thevalve 243 d. An inert gas supply system mainly includes the gas supplypipes 232 e and 232 f, the MFCs 241 e and 241 f, and the valves 243 eand 243 f.

In Step A to be described below, the fluorine-based gas supply systemfunctions as a first gas supply system that supplies a first gasincluding a fluorine-based gas into the process container. In Step A, asthe first gas, a fluorine-based gas and a nitrogen oxide-based gas canbe mixed and used in the process container Therefore, the nitrogen oxidegas supply system may be included in the first gas supply system.Further, in step B to be described below, the inert gas supply systemfunctions as a second gas supply system that supplies a second gas thatdoes not make chemical reaction with fluorine under a second temperatureto be described below. In addition, in step C to be described below, thenitrogen oxide gas supply system functions as a third gas supply systemthat supplies a third gas that makes chemical reaction with fluorineunder a third temperature to be described below.

One or all of the above-described various supply systems may beconfigured as an integrated-type supply system 248 in which the valves243 a to 243 f, the MFCs 241 a to 241 f, and so on are integrated. Hieintegrated-type supply system 248 is connected to each of the gas supplypipes 232 a to 232 f. In addition, the integrated-type supply system 248may be configured such that operations of supplying various gases intothe gas supply pipes 232 a to 232 f (that is, opening/closing operationof the valves 243 a to 243 f, flow rate adjustment operation by the MFCs241 a to 241 f, and the like) are controlled by a controller 121 whichwill be described below. The integrated-type supply system 248 isconfigured as an integral type or detachable-type integrated unit, andmay be attached to and detached from the gas supply pipes 232 a to 232 fand the like on an integrated unit basis, so that the maintenance,replacement, extension, etc. of the integrated-type supply system 248can be performed on an integrated unit basis.

An exhaust port 231 a for exhausting the internal atmosphere of theprocess chamber 201 is installed below the sidewall of the reaction tube203. The exhaust port 231 a may be installed from a lower portion of thesidewall of the reaction tube 203 to an upper portion thereof, that is,along the wafer arrangement region. An exhaust pipe 231 is connected tothe exhaust port 231 a. The exhaust pipe 231 is made of, for example, ametal material such as SUS. A vacuum exhaust device, e.g., a vacuum pump246, is connected to the exhaust pipe 231 via a pressure sensor 245,which is a pressure detector (pressure-detecting part) for detecting theinternal pressure of the process chamber 201, and an APC (auto pressurecontroller) valve 244, which is a pressure regulator (pressureadjustment part). The APC valve 244 is configured to perform or stop avacuum-exhausting operation in the process chamber 201 byopening/closing the valve while the vacuum pump 246 is actuated, and isalso configured to adjust the internal pressure of the process chamber201 by adjusting an opening degree of the valve based on pressureinformation detected by the pressure sensor 245 while the vacuum pump246 is actuated. An exhaust system mainly includes the exhaust pipe 231,the APC valve 244, and the pressure sensor 245. The exhaust system mayinclude the vacuum pump 246.

A seal cap 219, which serves as a furnace opening cover configured tohermetically seal a lower end opening of the manifold 209, is installedunder the manifold 209. The seal cap 219 is made of, for example, ametal material such as stainless steel (SUS) or the like, and is formedin a disc shape. An O-ring 220 b, which is a seal member making contactwith the lower end portion of the manifold 209, is installed on an uppersurface of the seal cap 219. A rotation mechanism 267 configured torotate a boat 217, which will be described below, is installed under theseal cap 219. A rotary shaft 255 of the rotation mechanism 267, which ismade of a metal material such as SUS or the like, is connected to theboat 217 through the seal cap 219. Tire rotation mechanism 267 isconfigured to rotate the wafers 200 by rotating the boat 217. The sealcap 219 is configured to be vertically moved up and down by a boatelevator 115 which is an elevating mechanism installed outside thereaction tube 203. The boat elevator 115 is configured as a transferdevice (transfer mechanism) which loads/unloads (transfers) the wafers200 into/out of the process chamber 201 by moving the seal cap 219 upand down. A shutter 219 s, which serves as a furnace opening coverconfigured to hermetically seal a lower end opening of the manifold 209in a state where the seal cap 219 is lowered and the boat 217 isunloaded from the process chamber 201, is installed under the manifold209. The shutter 219 s is made of, for example, a metal material such asstainless steel (SUS) or the like, and is formed in a disc shape. AnO-ring 220 c, which is a seal member making contact with the lower endportion of the manifold 209, is installed on an upper surface of theshutter 219 s. The opening/closing operation (such as elevationoperation, rotation operation, or the like) of the shutter 219 s iscontrolled by a shutter-opening/closing mechanism 115 s.

The exhaust pipe 231, the manifold 209, the seal cap 219, the rotaryshaft 255, the shutter 219 s, and so on may be made of an alloy havingexcellent heat resistance and corrosion resistance. An example of thealloy used may include Hastelloy® whose heat resistance and corrosionresistance are enhanced by adding iron (Fe), molybdenum (Mo), chromium(Cr), etc. to nickel (Ni), Inconel® whose heat resistance and corrosionresistance are enhanced by adding Fe, Cr, niobium (Nb), Mo, etc to Ni,or the like, in addition to SUS.

The boat 217 serving as a substrate support is configured to support aplurality of wafers 200, for example, 25 to 200 wafers, in such a statethat the wafers 200 are arranged in a horizontal posture and in multiplestages along a vertical direction with the centers of the wafers 200aligned with one another. As such, the boat 217 is configured to arrangethe wafers 200 to be spaced apart from each other. The boat 217 is madeof a heat resistant material such as quartz or SiC. Heat insulatingplates 218 made of a heat resistant material such as quartz or SiC areinstalled below the boat 217 in multiple stages.

A temperature sensor 263 serving as a temperature detector is installedin the reaction tube 203. Based on temperature information detected bythe temperature sensor 263, a state of supplying electric power to theheater 207 is adjusted such that an inside of the process chamber 201has a desired temperature distribution. The temperature sensor 263 isinstalled along the inner wall of the reaction tube 203.

As illustrated in FIG. 3 , a controller 121, which is a control part(control means), may be configured as a computer including a CPU(central processing unit) 121 a, a RAM (random access memory) 121 b, amemory device 121 c, and an I/O port 121 d. The RAM 121 b, the memorydevice 121 c, and the I/O port 121 d are configured to exchange datawith the CPU 121 a via an internal bus 121 e. An input/output device 122formed of, e.g., a touch panel or the like, is connected to thecontroller 121.

The memory device 121 c is configured by, for example, a flash memory, aHDD (hard disk drive), or the like. A control program for controllingoperations of a substrate processing apparatus, a process recipe inwhich sequences and conditions of substrate processing to be describedbelow are written, and a cleaning recipe in which sequences andconditions of a cleaning process to be described below are written, arereadably stored in the memory device 121 c. The process recipe functionsas a program for causing the controller 121 to execute each sequence inthe substrate processing, which will be described below, to obtain anexpected result. The cleaning recipe functions as a program for causingthe controller 121 to execute each sequence in the cleaning process,which will be described below, to obtain an expected result.Hereinafter, the process recipe, the cleaning recipe and the controlprogram may be generally and simply referred to as a “program.”Furthermore, the process recipe and the cleaning recipe may be simplyreferred to as a “recipe.” When the term “program” is used herein, itmay indicate a case of including the recipe, a case of including thecontrol program, or a case of including both the recipe and the controlprogram. The RAM 121 b is configured as a memory area (work area) inwhich a program, data, or so on read by the CPU 121 a is temporarilystored.

The I/O port 121 d is connected to the MFCs 241 a to 241 f, the valves243 a to 243 f, the pressure sensor 245, the APC valve 244, the vacuumpump 246, the temperature sensor 263, the heater 207, the rotationmechanism 267, the boat elevator 115, the shutter-opening/closingmechanism 115 s, and so on.

The CPU 121 a is configured to read and execute the control program fromthe memory device 121 c The CPU 121 a is also configured to read therecipe from the memory device 121 c according to an input and so on ofan operation command from the input/output device 122. In addition, theCPU 121 a is configured to control the flow-rate-adjusting operation ofvarious kinds of gases by the MFCs 241 a to 241 f, the opening/closingoperation of the valves 243 a to 243 f, the opening/closing operation ofthe APC valve 244, the pressure-adjusting operation performed by the APCvalve 244 based on the pressure sensor 245, the actuating and stoppingof the vacuum pump 246, the temperature-adjusting operation performed bythe heater 207 based on the temperature sensor 263, the operation ofrotating the boat 217 with the rotation mechanism 267 and adjusting therotation speed of the boat 217, the operation of moving the boat 217 upand down by the boat elevator 115, the opening/closing operation of theshutter 219 s by the shutter-opening/closing mechanism 115 s, and so on,according to contents of the read recipe.

The controller 121 may be configured by installing, on the computer, theaforementioned program stored in an external memory device 123 (forexample, a magnetic disk such as an HDD, an optical disc such as a CD, amagneto-optical disc such as an MO, or a semiconductor memory such as aUSB memory). The memory device 121 c or the external memory device 123is configured as a non-transitory computer-readable recording medium.Hereinafter, the memory device 121 c and/or the external memory device123 may be generally and simply referred to as a “recording medium.”When the term “recording medium” is used herein, it may indicate a caseof including the memory device 121 c, a case of including the externalmemory device 123, or a case of including both the memory device 121 cand the external memory device 123. Furthermore, the program may beprovided to the computer using communication means such as the Internetor a dedicated line, instead of using the external memory device 123.

(2) Substrate-Processing Process

A substrate-processing sequence example of forming a film over a wafer200 as a substrate using the aforementioned substrate processingapparatus, that is, a film-forming sequence example, which is one of theprocesses for manufacturing a semiconductor device, will be described.In the following descriptions, the operations of the respective partsconstituting the substrate processing apparatus are controlled by thecontroller 121.

In the film-forming sequence according to the present embodiments, asilicon nitride film (SiN film), which is a film containing Si and N, isformed as a film over the wafer 200 by performing a cycle apredetermined number of times, the cycle including non-simultaneouslyperforming; step 1 of supplying an HODS gas as a precursor to the wafer200 in the process container, and step 2 of supplying an NH₃ gas as areactant to tire wafer 200 in the process container.

In the present disclosure, for the sake of convenience, the film-formingsequence may be denoted as follows. The same denotation may be used inmodification examples to be described below.(HCDS→NH₃)×n⇒SiNWhen the term “wafer” is used in the present disclosure, it may refer to“a wafer itself” or “a wafer and a laminated body of certain layers orfilms formed over a surface of the wafer.” When the phrase “a surface ofa wafer” is used in the present disclosure, it may refer to “a surfaceof a wafer itself” or “a surface of a certain layer formed over awafer”. When the expression “a certain layer is formed over a wafer” isused in the present disclosure, it may mean that “a certain layer isformed directly on a surface of a wafer itself” or that “a certain layeris formed on a layer formed over a wafer.” When the term “substrate” isused in the present disclosure, it may be synonymous with the term“wafer.”(Wafer Charging and Boat Loading)

When a plurality of wafers 200 are charged on the boat 217 (wafercharging), the shutter 219 s is moved by the shutter-opening-closingmechanism 115 s, and the lower end opening of the manifold 209 is opened(shutter open). Then, as illustrated in FIG. 1 , the boat 217 supportingthe plurality of wafers 200 is lifted up by the boat elevator 115 to beloaded into the process chamber 201 (boat loading). In this state, theseal cap 219 seals the lower end of the manifold 209 via the O-ring 220b.

(Pressure Adjustment and Temperature Adjustment)

The inside of the process chamber 201, that is, a space in which thewafers 200 are placed, is vacuum-exhausted (depressurization-exhausted)by the vacuum pump 246 to reach a desired pressure (degree of vacuum).In this operation, the internal pressure of the process chamber 201 ismeasured by the pressure sensor 245. The APC valve 244 isfeedback-controlled based on the measured pressure information. Thewaters 200 in the process chamber 201 are heated by the heater 207 to adesired temperature. In this operation, the state of supplying electricpower to the heater 207 is feedback-controlled based on the temperatureinformation detected by die temperature sensor 263 such that the insideof the process chamber 201 has a desired temperature distribution. Therotation of the wafers 200 by the rotation mechanism 267 is dienstarted. Exhausting the inside of the process chamber 201 and heatingand rotating the wafers 200 may be continuously performed at least untilprocessing of the wafers 200 is completed.

(Film Forming Step)

The following steps 1 and 2 are then performed in a sequential manner.

[Step 1]

In this step, an HCDS gas is supplied to the wafer 200 in the processchamber 201 (HCDS gas supplying step) Specifically, the valve 243 a isopened to allow the HCDS gas to flow through the gas supply pipe 232 a.The flow rate of the HCDS gas is adjusted by the MFC 241 a, and then theHCDS gas is supplied into the process chamber 201 via the nozzle 249 aand is exhausted through the exhaust port 231 a. In this operation, theHCDS gas is supplied to the wafer 200. At this time, the valves 243 eand 243 f may be opened to supply a N: gas into the process chamber 201via the nozzles 249 a and 249 b.

The example of the process condition in this step is described asfollows.

-   -   Supply flow rate of HCDS gas: 0.01 to 2 slm, specifically 0.1 to        1 slm    -   Supply flow rate of N₂ gas (for each gas supply pipe): 0 to 10        slm    -   Gas supply time of each gas: 1 to 120 seconds, specifically 1 to        60 seconds    -   Processing temperature: 250 to 800 degrees C., specifically 400        to 700 degrees C.    -   Processing pressure: 1 to 2,666 Pa, specifically 67 to 1,333 Pa

In the present disclosure, the notation of a numerical range such as“250 to 400 degrees C.” means that the lower limit value and the upperlimit value are included in the range. For example, “250 to 800 degreesC.” means “equal to or higher than 250 degrees C. and equal to or lowerthan 800 degrees C.” The same applies to other numerical ranges.

By supplying the HCDS gas to the wafer 200 under the aforementionedcondition, a Si-containing layer containing Cl is formed as a firstlayer over the outermost surface of the wafer 200. The Si-containinglayer containing Cl is formed when HCDS is physically adsorbed on theoutermost surface of the wafer 200, when a substance (hereinafter,Si_(x)Cl_(y)) into which HCDS is partially decomposed is chemicallyadsorbed thereon, or when Si is deposited thereon by thermaldecomposition of HCDS. The Si-containing layer containing Cl may be anadsorption layer (physical adsorption layer or chemical adsorptionlayer) of HCDS or Si_(x)Cl_(y), or may be a Si layer (Si depositionlayer) containing Cl. In the present disclosure, a Si-containing layercontaining Cl is simply referred to as a Si-containing layer.

After the first layer is formed, the valve 243 a is closed to stop thesupply of the HCDS gas into the process chamber 201. Then, the inside ofthe process chamber 201 is vacuum-exhausted, and a gas and the likeremaining in the process chamber 201 are excluded from the inside of theprocess chamber 201 (purge step). At this time, the valves 243 e and 243f are opened to supply a N₂ gas into the process chamber 201. The N₂ gasacts as a purge gas.

As the precursor, in addition to the HCDS gas, it may be possible touse, e.g., chlorosilane-based gases such as a monochlorosilane (SiH₃Cl,abbreviation: MCS) gas, a dichlorosilane (SiH₂Cl₂, abbreviation: DCS)gas, a trichlorosilane (SiHCl₃, abbreviation: TCS) gas, atetrachlorosilane (SiCl₄, abbreviation: STC) gas, an octachlorotrisilane(Si₃Cl₈, abbreviation: OCTS) gas, and the like. Like the HCDS gas, thesegases are gases that can deposit a film alone under the aforementionedprocess condition.

Example of the inert gas may include a rare gas such as Ar gas. He gas.Ne gas, Xe gas, or the like, in addition to the N₂ gas. Tire sameapplies to step 2 and a cleaning process, which will be described below.

[Step 2]

After Step 1 is ended, an NH₃ gas is supplied to the wafer 200 in theprocess chamber 201, specifically, the first layer formed over the wafer200 (NH₃ gas supplying step). Specifically, the valve 243 b is opened toallow the NH₃ gas to flow through the gas supply pipe 232 b. The flowrate of the NH₃ gas is adjusted by the MFC 241 b, and then the NH₃ gasis supplied into the process chamber 201 via the nozzle 249 b and isexhausted through the exhaust port 231 a. In this operation, the NH₃ gasis supplied to the wafer 200. At this time, the valves 243 e and 243 fmay be opened to supply a N₂ gas into the process chamber 201 via thenozzles 249 a and 249 b.

The example of the process condition in this step is described asfollows

-   -   Supply flow rate of NH₃ gas: 0.1 to 10 slm    -   Supply flow rate of N₂ gas (for each gas supply pipe): 0 to 2        slm    -   Supply time of NH₃ gas: 1 to 120 seconds, specifically 1 to 60        seconds

Processing pressure: 1 to 4,000 Pa, specifically 1 to 3,000 Pa

The other process condition is the same as the process condition in Step1.

By supplying the NH₃ gas to the wafer 200 under the aforementionedcondition, at least a portion of the first layer formed over the wafer200 is nitrided (modified). As the first layer is modified, a secondlayer containing Si and N, that is, a SiN layer, is formed over thewafer 200. When the second layer is formed, impurities such as Clcontained in the first layer constitute a gaseous substance containingat least Cl in the process of the modifying reaction of the first layerby the NH₃ gas, and are discharged from the process chamber 201. As aresult, the second layer becomes a layer having fewer impurities such asCl and the like than the first layer.

After the second layer is formed, the valve 243 b is closed to stop thesupply of the NH₃ gas into the process chamber 201. Then, a gas and thelike remaining in the process chamber 201 are excluded from the insideof the process chamber 201 according to the same processing procedure asthe purge step in Step 1 (purge step).

As the reactant, in addition to the NH₃ gas, it may be possible to use,e.g., hydrogen nitride-based gases such as a diazene (N₂H₂) gas, ahydrazine (N₃H₄) gas, a N₃H₈ gas, and the like.

(Performing Predetermined Number of Times)

A cycle that non-simultaneously (i.e., asynchronously) performs theabove-described steps 1 and 2 is performed a predetermined number oftimes (m times, m being an integer of one or larger) to thereby form aSiN film having a predetermined composition and a predetermined filmthickness over the wafer 200. This cycle may be repeated a plurality oftimes. That is to say, a thickness of the second layer formed per onecycle may be set to be smaller than a desired film thickness. Thus, theabove cycle may be repeated a plurality of times until a film thicknessof the SiN film formed by laminating the second layers becomes equal tothe desired film thickness.

(After-Purging and Returning to Atmospheric Pressure)

After the film forming step is ended, a N₂ gas as a purge gas issupplied into the process chamber 201 from each of the nozzles 240 a and249 b and is exhausted through the exhaust port 231 a. Thus, the insideof the process chamber 201 is purged, and the residual gas and thereaction byproducts remaining in the process chamber 201 are removedfrom the inside of the process chamber 201 (after-purging). The internalatmosphere of the process chamber 201 is then substituted with an inertgas (inert gas substitution) and the internal pressure of the processchamber 201 is returned to the atmospheric pressure (returning toatmospheric pressure).

(Boat Unloading and Wafer Discharging)

The seal cap 219 is then moved down by the boat elevator 115 to open thelower end of the manifold 209. In addition, the processed wafers 200supported by the boat 217 are unloaded from the lower end of themanifold 209 to the outside of the reaction tube 203 (boat unloading).After the boat unloading, the shutter 219 s is moved, and the lower endopening of the manifold 209 is sealed by the shutter 219 s via theO-ring 220 c (shutter closing). After being unloaded from the reactionlube 203, the processed wafers 200 are discharged from the boat 217(wafer discharging).

(3) Cleaning-Processing Process

When the above-described substrate processing is performed, depositsincluding a thin film such as a SiN film accumulate in the inside of theprocess container, for example, on the inner w all of the reaction tube203, the surfaces of the nozzles 249 a and 249 b, the surface of theboat 217, and so on. That is, the deposits including the thin filmadhere to and accumulate on the surfaces of the members in the processchamber 201 healed to a film-forming temperature. Therefore, in thepresent embodiments, when the amount of deposit accumulated in theprocess container, that is, the accumulated film thickness, reaches apredetermined amount (thickness) before the deposits peel off or drop,the inside of the process container is cleaned.

The cleaning process of these embodiments includes:

Step A of removing substances adhered in a process container set at afirst temperature after processing a wafer 200 as a substrate, that is,the above-mentioned deposits, by supplying a first gas including afluorine-based gas at a first flow rate into the process container toexhaust the inside of the process container;

Step B of physically desorbing and removing residual fluorine in theprocess container set at a second temperature higher than the firsttemperature after performing Step A by supplying a second gas, whichdoes not react chemically with fluorine under the second temperature, ata second flow rate higher than the first flow rate and a third flow rate(which will be described below) into the process container to exhaustthe inside of the process chamber; and

Step C of chemically desorbing and removing residual fluorine in theprocess container set at a third temperature higher than the firsttemperature after performing Step A by supplying a third gas, whichreacts chemically with fluorine under the third temperature, at thethird flow rate into the process chamber to exhaust the inside of theprocess chamber.

Hereinafter, an example of the cleaning process using a F₂ gas and a NOgas (F₂ gas+NO gas) as the first gas, a N₂ gas as the second gas, and aNO gas as the third gas will be described with reference to FIG. 4 . Inthe following description, the operations of various parts constitutingthe substrate processing apparatus are controlled by the controller 121.

(Boat Loading)

The shutter 219 s is moved by the shutter-opening/closing mechanism 115s and the lower end opening of the manifold 209 is opened (shutteropen). Then, an empty boat 217, that is, a boat 217 not loaded with awafer 200, is lifted up by the boat elevator 115 to be loaded into theprocess chamber 201. In this state, the seal cap 219 seals the lower endof the manifold 209 via the O-ring 220 b.

(Pressure Adjustment and Temperature Adjustment)

The inside of the process chamber 201 is vacuum-exhausted by the vacuumpump 246 to reach a desired pressure (degree of vacuum), la addition,the inside of the process chamber 201 is heated by the heater 207 to adesired first temperature. At this time, members in the process chamber201, that is, the inner wall of the reaction tube 203, the surfaces ofthe nozzles 249 a and 249 b, the surface of the boat 217, and so on, arealso heated to the first temperature. Further the rotation of the boat217 by the rotation mechanism 267 is started. The operation of thevacuum pump 246, the heating of the inside of the process chamber 201,and the rotation of the boat 217 are continuously performed until stepsA to C to be described below are completed. The boat 217 may not berotated.

(Step A: F₂ gas+NO Gas Supplying)

After the internal pressure and temperature of the process chamber 201are stabilized, Step A is started. In this step, a F₂ gas and a NO gasare supplied at a First flow rate into the process container set to theFirst temperature to exhaust the inside of the process chamber.Specifically, the valves 243 c and 243 d are opened to allow the F₂ gasto flow into the gas supply pipe 232 c and the NO gas to flow into thegas supply pipe 232 d. The flow rates of the F₂ gas and the NO gas areadjusted by the MFCs 241 c and 241 d, respectively, and the F₂ gas andthe NO gas are supplied into the process chamber 201 via the gas supplypipes 232 a and 232 b and the nozzles 249 a and 249 b, respectively. Atthe same time, the valves 243 e and 243 f may be opened to supply a N₂gas into the process chamber 201 via the nozzles 249 a and 249 b.

The example of the process condition in Step A is described as follows.

-   -   Supply flow rate of F₂ gas (first flow rate): 0.5 to 10 slm    -   Supply flow rate of NO gas (first flow rate): 0.5 to 10 slm    -   Supply flow rate of N₂ gas: 0.01 to 20 slm    -   Gas supply time of each gas: 1 to 60 minutes, specifically 10 to        20 minutes    -   Processing temperature (First temperature): 100 to 500 degrees        C., specifically 250 to 350 degrees C.    -   Processing pressure (first pressure): 1,333 to 10.000 Pa,        specifically 1,333 to 16,665 Pa

By supplying the F₂ gas and the NO gas into the process chamber 201under the aforementioned processing condition, the NO gas can be addedto the F₂ gas, and these gases can be mixed and reacted in the processchamber 201. This reaction makes it possible to generate for example,active species such as fluorine radicals (F*) and nitrosyl fluoride(FNO) (hereinafter collectively referred to as FNO or the like) in theprocess chamber 201. As a result, a mixed gas obtained by adding FNO orthe like to the F₂ gas is present in the process chamber 201. The mixedgas obtained by adding FNO or the like to the F₂ gas contacts themembers in the process chamber 201, for example, the inner wall of thereaction tube 203, the surfaces of the nozzles 249 a and 249 b, tiresurface of the boat 217, and the like. At this time, the depositsadhered to the members in the process chamber 201 can be removed by thethermochemical reaction (etching reaction). FNO or the like acts topromote the etching reaction by the F₂ gas to increase the etching rateof the deposits, that is, to assist the etching.

As the fluorine-based gas, in addition to the F₂ gas, it may be possibleto use. e.g., a hydrogen fluoride (HP) gas, a nitrogen fluoride (NF₃)gas, a chlorine fluoride (ClF₃), or a mixed gas thereof. As the gas 10be added to the fluorine-based gas, in addition to the NO gas, it may bepossible to use, e.g., a hydrogen (H₂) gas, an oxygen (O₂) gas, anitrous oxide (N₂O) gas, an isopropyl alcohol ((CH₃)₂CHOH, abbreviation:IPA) gas, a methanol (CH₃OH) gas or water vapor (H₂O gas).

(Purge and Temperature Increasing Step)

After a predetermined time has elapsed and the removal of the depositsfrom the process container is completed, the valves 243 c and 243 d areclosed to slop the supply of the F₂ gas and the NO gas into the processchamber 201. Then, the gas and the like remaining in the process chamber201 are excluded from the inside of the process chamber 201 according tothe same processing procedure as the purge step in Step 1 (purge step).

However, even when this purge step is performed for a long time, it isdifficult to completely remove fluorine from the inside of the processcontainer. This is because, at the end of Step A, fluorine is physicallyadsorbed or chemically adsorbed on the surfaces of the members in theprocess container. The residual fluorine adsorbed on the surfaces of themembers in the process container tends to remain m the process containerwithout being desorbed from the surfaces of the members even when thesame step as the above-described purging step of Step 1 andafter-purging is performed for a long time (for example, 5 to 10 hours)under the first temperature. The fluorine remaining in the processcontainer is one factor that reduces the productivity of the nextsubstrate processing (batch processing) to be performed after thecleaning process. Specifically, when the above-described substrateprocessing is repeatedly performed after the cleaning process, thedeposition rate of a SiN film formed over the wafer 200 may dropsignificantly due to the influence of residual fluorine in the processcontainer in at least the first several substrate processings.

In order to solve this problem, in the present embodiments, after Step Ais performed. Steps B and C to be described below are performed. Byperforming Step B, the residual fluorine in the process container, whichwas difficult to remove even when the above-described purge step isperformed for a long time, can be physically desorbed from the surfacesof the members in the process container and removed from the inside ofthe process container. Further, by performing Step C, the residualfluorine in the process container, which was difficult to remove evenwhen the above-described purge step is performed for a long time, can bechemically desorbed from the surfaces of the members in the processcontainer and removed from the inside of the process container. As willbe described below, it is preferable to perform Step C after Step B toefficiently remove the residual fluorine in the process container. Thatis, it is preferable to perform Step B after Step A and to perform StepC after Step B. That is, it is preferable to perform Step A, Step B, andStep C continuously in this order.

In order to exert the above-described operation in Step B, it isnecessary to set the internal temperature of the process container to asecond temperature higher than the aforementioned first temperature.Further, in order to exert the above-described operation in Step C, itis necessary to set the internal temperature of the process container toa third temperature higher than the aforementioned first temperature. Asdescribed above, in the present embodiments, since Steps A, B, and C areperformed in this order, here, the output of the heater 207 is adjusted,and the internal temperature of the process chamber 201 is firstincreased to a temperature required to properly advance Step B, that is,the second temperature higher than the first temperature (temperatureincreasing step). In addition, it is preferable to start Step B to bedescribed below after the internal temperature of the process chamber201 reaches the second temperature and is stabilized. By waiting for theinternal temperature of the process chamber 201 to be stabilized at thesecond temperature, since the entire region in the process container canbe uniformly heated to the second temperature and Step B to be describedbelow can be performed in that state, it is possible to uniformly obtainthe operation of the below-described Step B of physically desorbing andremoving the residual fluorine in the process container throughout theentire region in the process container.

(Step B: Large Flow Rate N₂ Purging)

In this step, a N₂ gas, which does not react chemically with fluorineunder the second temperature, is supplied at a second flow rate higherthan the aforementioned first flow rate and a third flow rate to bedescribed below into the process container set at the second temperaturehigher than the first temperature to exhaust the inside of the processcontainer. Specifically, the valves 243 e and 243 f are opened to allowthe N₂ gas to flow into the gas supply pipes 232 e and 232 f,respectively. The flow rate of the N₂ gas is adjusted by the MFCs 241 eand 241 f, and the N₂ gas is supplied into the process chamber 201 viathe gas supply pipes 232 a and 232 b and the nozzles 249 a and 249 b(large flow rate N₂ purge). The second flow rate used herein refers tothe total flow rate of N₂ gas supplied into the process container, thatis, the sum of flow rates of N₂ gases supplied via the nozzles 249 a and249 b.

The example of the process condition in Step B is described as follows.

-   -   Supply flow rate of N₂ gas (second flow rate): 5 to 50 slm    -   Supply time of N₂ gas: 1 to 300 minutes, specifically 30 to 120        minutes    -   Processing temperature (second temperature): 500 to 800 degrees        C.    -   Processing pressure (second pressure): 13 to 1,333 Pa

By supplying the N₂ gas into the process container under the secondtemperature higher than the first temperature and at the second flowrate higher than the first flow rate and the third flow rate, in a statewhere high thermal energy is given to the residual fluorine in theprocess container, it is possible to collide the N₂ gas supplied at alarge flow rate with the residual fluorine. That is, it is possible tocollide molecules of the N₂ gas with the residual fluorine whoseadsorption power is reduced by giving high thermal energy, at a highflow velocity and with high probability. As a result, it is possible tophysically desorb and remove the residual fluorine from the inside ofthe process container efficiently and effectively. The desorbed residualfluorine is discharged through the exhaust port 231 a.

By performing this step, most or all of the residual fluorine physicallyadsorbed on the surfaces of the members in the process container can bephysically desorbed and removed from the inside of the processcontainer. Further, in this step, it is also possible to physicallydesorb and remove not only the residual fluorine physically adsorbed onthe surfaces of the members in the process container but also some ofthe residual fluorine chemically adsorbed on the surfaces of themembers. However, even when this step is performed for a long time, itis difficult to completely desorb all the residual fluorine chemicallyadsorbed on the surfaces of the members in the process containerTherefore, after performing this step for a predetermined time, Step Cto be described below is performed.

As the second gas, in addition to the N₂ gas, it may be possible to use,e.g., rare gases such as a He gas, an Ar gas, a Ne gas, a Xe gas, andthe like.

(Step C: NO Purge)

In this step, a NO gas that reacts chemically with fluorine under athird temperature is supplied at a third flow rate into the processcontainer set to the third temperature higher than the first temperatureto exhaust the inside of the process container Specifically, the valve243 d is opened to allow the NO gas to flow into the gas supply pipe 232d. The flow rate of the NO gas is adjusted by the MFC 241 d, and the NOgas is supplied into the process chamber 201 via the gas supply pipe 232b and the nozzle 249 b (NO purge).

The example of the process condition in Step C is described as follows.

-   -   Supply flow rate of NO gas (third flow rate): 0.01 to 10 slm    -   Supply time of NO gas: 1 to 120 minutes, specifically 30 to 60        minutes    -   Processing temperature (third temperature): 500 to 750 degrees        C.    -   Processing pressure (third pressure): 13 to 2,000 Pa

By supplying the NO gas under the third temperature higher than thefirst temperature, it is possible to supply the NO gas with the residualfluorine chemically adsorbed in the process container and cause them toreact chemically. As a result, it is possible to promote the chemicaldesorption of the residual fluorine in the process container. Thedesorbed residual fluorine is discharged through the exhaust port 231 a.

By performing this step, it is possible to remove most or all of theresidual fluorine chemically adsorbed on the surfaces of the members inthe process container from the inside of the process container. Thus, inStep C, the residual fluorine that could not be all removed in Step Bcan be chemically desorbed and removed. In this step, it is alsopossible to not only desorb the residual fluorine chemically adsorbed onthe surfaces of the members in the process container but also chemicallydesorb and remove some of the residual fluorine physically adsorbed onthe surfaces of the members. However, in order to remove the residualfluorine physically adsorbed on the surfaces of the members in theprocess container. Step B is more advantageous than Step C in view ofthe removal efficiency and the gas cost. Therefore, as the presentembodiments, it is preferable to perform Step B prior to Step C andremove the residual fluorine, which could not be all removed in Step B,in Step C.

As described above, by sequentially performing Step B of physicallydesorbing and removing the residual fluorine and Step C of chemicallydesorbing and removing the residual fluorine, it is possible todischarge the residual fluorine in the process container from the insideof the process container with high efficiency and at low costs.

The processing pressure (third pressure) in this step is preferably setto a pressure larger than the aforementioned second pressure (thirdpressure>second pressure). By setting the processing pressure in thisstep in this manner, it is possible to enhance the reactivity betweenthe residual fluorine and the NO gas in the process container and topromote the reaction between them. As a result, chemical desorption ofthe residual fluorine from the inside of the process container isfurther promoted, which makes it possible to remove the residualfluorine in the process container from the inside of the processcontainer efficiently and effectively. Further, by setting theprocessing pressure (third pressure) in this step to a large pressure asdescribed above, the residence time of the NO gas in the processcontainer can be extended, and the NO gas can be spread to every cornerin the process container. This makes it possible to uniformly remove theresidual fluorine from the entire region in the process container. Thatis, the operation of Step C of chemically desorbing and removing theresidual fluorine in the process container can be uniformly obtained inthe entire region in the process container.

The processing temperature (third temperature) in this step ispreferably equal to the processing temperature (second temperature) inStep B (third temperature second temperature). The third temperature maybe set to be equal to z film-forming temperature (a processingtemperature when processing the wafer 200) (third temperature=secondtemperature=film-forming temperature). By setting the processingtemperature in this step in this manner, it is not necessary to providea step of changing the internal temperature of the process container,and it is possible to save the time required for increasing/decreasingthe internal temperature of the process container, thereby shorteningthe processing time so much. This makes it possible to reduce thedowntime of the substrate processing apparatus. The third temperaturemay be set to be higher than the second temperature (thirdtemperature>second temperature), in which case, in Step C, the reactionbetween the residual fluorine and the NO gas in the process containercan be further promoted, which makes it possible to further enhance theoperation of chemically desorbing and removing the residual fluorine.Further, the second temperature may be set to be higher than the thirdtemperature (second temperature>third temperature), in which case, inStep B, the residual fluorine in the process container may be moreeasily desorbed, which makes it possible to further enhance theoperation of physically removing and removing the residual fluorine.

As the third gas, in addition to the NO gas, it may be possible to use,e.g., nitrogen oxide gases such as a N₂O gas, a nitrogen dioxide (NO₂)gas, and the like. Even when a H₂ gas or an NH₃ gas is used as the thirdgas, it is possible to react the residual fluorine with the third gas toremove the residual gas from the inside of the process container.However, when these gases are used as the third gas, HF or the like isgenerated by the reaction between the residual fluorine and the thirdgas in the process container, and may cause etching damage to themembers (particularly quart/members) in the process container. As thepresent embodiments, using the nitrogen oxide-based gas not containinghydrogen as the third gas makes it possible to solve the above-mentionedproblems

(After-Purging and Returning to Atmospheric Pressure)

After Steps A to C are ended, the inside of the process chamber 201 ispurged (after-purging) according to the same processing procedure as theabove-described after-purging in the substrate-processing process. Theinternal atmosphere of the process chamber 201 is then substituted withan inert gas (inert gas substitution) and the internal pressure of theprocess chamber 201 is returned to the atmospheric pressure (returningto atmospheric pressure).

(Boat Unloading)

The seal cap 219 is moved down by the boat elevator 115 to open thelower end of the manifold 209. Then, an empty boat 217 is unloaded fromthe lower end of the manifold 209 to the outside of the reaction tube203 (boat unloading). When these series of processes are ended, theabove-described substrate-processing process is resumed.

(Pre-Coating)

In addition, prior to resuming the above-described substrate-processingprocess, it is preferable to form a pre-coating layer (SiN layer)containing Si and N over the surfaces of the members in the processcontainer (pre-coating) by performing a process on the wafer 200 in theprocess container set at a fourth temperature after Step C, that is, thesame process as the film forming step of the above-describedsubstrate-processing process. This process is preferably performed in astate where the empty boat 217 after the cleaning process isaccommodated in the process container.

The fourth temperature may be set to be equal to the second temperatureor the third temperature. For example, the fourth temperature may be setto be equal to the second temperature and the third temperature (fourthtemperature=third temperature=second temperature). Further, the fourthtemperature may also be set to be equal to the film-forming temperature(the processing temperature when processing the wafer 200) (fourthtemperature third temperature second temperature=film-formingtemperature). By setting the fourth temperature to such a temperature,it is not necessary to provide a step of changing the internaltemperature of the process container, and it is possible to save thetime required for increasing/decreasing the internal temperature of theprocess container, thereby shortening the processing time so much. Thismakes it possible to shorten the downtime of the substrate processingapparatus. In addition, it is preferable to perform the pre-coating in aperiod before performing the above-mentioned boat unloading afterperforming Step C.

(4) Effects of the Present Embodiments

According to the present embodiments, one or more effects set forthbelow may be achieved.

(a) By performing Step A and then performing Step B of supplying the N₂gas at the second flow rate higher than each of the first flow rate andthe third flow rate into the process container set at the secondtemperature higher than the first temperature to exhaust the inside ofthe process container, it is possible to physically desorb and removethe residual fluorine in the process container.

Further, by performing Step A and then performing Step C of supplyingthe NO gas at the third flow rate into the process container set at thethird temperature higher than the first temperature to exhaust theinside of the process container, it is possible to chemically desorb andremove the residual fluorine in the process container.

By the operations of these Steps B and C, it is possible to remove theresidual fluorine, which has been difficult to remove from the inside ofthe process container even when the same step as the above-describedpurging step of Step 1 and after-purging is performed for a long time,from the inside of the process container. By removing the residualfluorine from the process container, it is possible to resume thesubstrate processing without deteriorating the productivity of thesubstrate processing after performing the cleaning process. This makesit possible to shorten the downtime of the substrate processingapparatus.

(b) By starting Step B after the internal temperature of the processchamber 201 reaches the second temperature and is stabilized, theoperation of Step B of physically desorbing and removing the residualfluorine in the process container can be obtained uniformly throughoutthe entire region in the process container. If Step B is started beforethe internal temperature of the process chamber 201 reaches the secondtemperature and is stabilized, the operation of Step B of physicallydesorbing and removing the residual fluorine in the process containermay be performed unevenly depending on a temperature difference in theprocess container.

(c) By setting the internal pressure (third pressure) of the processcontainer in Step C to be higher than the internal pressure (secondpressure) of the process container in Step B (third pressure>secondpressure), it is possible to promote chemical desorption of the residualfluorine in the process container in Step C more than that in a case ofthird pressure≤second pressure. As a result, it is possible to furthershorten the above-mentioned downtime.

(d) By performing Step C after performing Step B, it is possible toefficiently remove the residual fluorine from the inside of the processcontainer. This makes it possible to further shorten the above-mentioneddowntime. In addition, it is possible to suppress an increase in gascost when removing the residual fluorine from the inside of the processcontainer.

(e) By setting the processing temperature (third temperature) in Step Cto be equal to the processing temperature (second temperature) in Step B(third temperature second temperature), it is not necessary to provide astep of changing the internal temperature of the process container, andit is possible to save the time required for increasing/decreasing theinternal temperature of the process container, thereby shortening theprocessing time so much. This makes it possible to further shorten theabove-mentioned downtime.

(f) By setting the processing temperature (third temperature) in Step Cto a temperature higher than the processing temperature (secondtemperature) in Step B (third temperature>second temperature), it ispossible to promote chemical desorption of the residual fluorine in theprocess container in Step C more than that in a case of third pressure≤;second pressure. In addition, by setting the processing temperature(second temperature) in Step B to a temperature higher than theprocessing temperature (third temperature) in Step C (secondtemperature>third temperature), it is possible to promote physicaldesorption of the residual fluorine in the process container in Step Bmore than that in a case of second pressure≤, third pressure.

(g) By performing the pre-coating before performing thesubstrate-processing process after performing Step C, it is possible tostabilize the film-forming rate and the quality of substrate processingwhen the next film-forming process is performed.

(h) By performing Steps A, B, and C under a non-plasma atmosphere, thatis, by performing these steps by adding thermal energy to the internalatmosphere of the process container without adding plasma energy, it ispossible to prevent the members in the process container from beingdamaged by plasma.

(i) The above-described effects can be obtained in the same manner whenthe above-mentioned first gas other than F₂ gas+NO gas is used in StepA, the above-mentioned second gas other than the N₂ gas is used in StepB, or the above-mentioned third gas other than the NO gas is used inStep C.

(5) Modification Examples

The cleaning process is not limited to the above-described aspect, butmay be changed as in the following modification examples which may beused in proper combination. Unless otherwise stated, the processingprocedure and processing condition in each step of each modificationexample may be the same as the processing procedure and processingcondition in each step shown in the above-described aspect.

First Modification Example

In Step B, a step of supplying a N₂ gas into the process container and astep of exhausting (vacuum-exhausting, or evacuating) the inside of theprocess container in a state where the supply of the N₂ gas into theprocess container is stopped may be alternately repeated plural times.That is, in Step B, a large flow rate of N₂ gas may be intermittentlysupplied into the process container to cycle-purge the inside of theprocess container.

The example of the process condition in Step B at this time is describedas follows.

-   -   N₂ gas supply time: 10 to 300 seconds/cycle, specifically 60 to        120 seconds/cycle    -   Vacuum-exhaust time: 10 to 300 seconds/cycle, specifically 60 to        120 seconds/cycle    -   Number of cycles: 1 to 300, specifically 30 to 120    -   Minimum pressure: 13 to 30 Pa    -   Maximum pressure: 30 to 1,333 Pa

The other process condition may be the same as the process condition inStep B of the above-described aspect.

This modification example can obtain the same effects as the cleaningprocess described with reference to FIG. 4 . In addition, according tothis modification example, it is possible to further promote physicaldesorption of the residual fluorine in the process container to removethe residual fluorine from the inside of the process container moreeffectively in Step B. As a result, it is possible to further shortenthe above-mentioned downtime.

Second Modification Example

Steps B and C may be alternately repeated plural times. Thismodification example also can obtain the same effects as the cleaningprocess described with reference to FIG. 4 . In addition, according tothis modification example, it is possible to remove the residualfluorine from the inside of the process container more effectively. As aresult, it is possible to further shorten the above-mentioned downtime.

Third Modification Example

When Steps B and C are alternately repeated plural times, the ratio ofexecution time of Step C to execution time of Step B may be changed. Forexample, when Steps B and C are alternately repeated plural times, theratio (TC/TB) of execution time TC of Step C to execution time TB ofStep B may be gradually increased. That is, when Steps B and C arealternately repeated plural times, the rate of chemically desorbing andremoving the residual fluorine may be gradually increased.

This modification example also can obtain the same effects as thecleaning process described with reference to FIG. 4 . In addition,according to this modification example, it is possible to moreefficiently and effectively remove the residual fluorine which could notbe all removed in Step B As a result, it is possible to further shortenthe above-mentioned downtime. Further, it is possible to appropriatelydecrease the amount of N₂ gas exhausted from the exhaust pipe 231without contributing to desorption of the residual fluorine in theprocess container, which can result in reduction in gas cost.

Fourth Modification Example

B may be performed after Step C. That is, Steps A, C, and B may beperformed continuously in this order. This modification example also canobtain substantially the same effects as the cleaning process describedwith reference to FIG. 4 . However, as described above, performing StepsA, B, and C in this order is advantageous in that the removal efficiencyof the residual fluorine from the inside of the process container ishigh and it is possible to suppress an increase in gas cost.

Other Embodiments

While some embodiments of the present disclosure have been described indetail above, the present disclosure is not limited to theaforementioned embodiments but may be differently modified withoutdeparting from the subject matter of the present disclosure.

The example in which the inside of the process container is cleanedafter the SiN film is formed over the wafer in the process container hasbeen described in the above embodiments. However, the present disclosureis not limited to such an aspect. For example, the above-describedcleaning process can be suitably applied to a case where the inside ofthe process container is cleaned after forming a silicon film (Si film),a silicon oxide film (SiO film), a silicon oxycarbonitride film (SiOCNfilm), a silicon oxycarbide film (SiOC film), a silicon oxynitride film(SiON film), a silicon carbonitride film (SiCN film), a siliconborocarbonitride film (SiBCN film), a silicon boronitride film (SiBNfilm), or the like over the wafer in the process container. Further, thefilm-forming method is not limited to the method of alternatelysupplying a precursor and a reactant to the wafer 200, but may be amethod of simultaneously and continuously supplying the precursor andthe reactant to the wafer 200 or a method of simultaneously andintermittently supplying the precursor and the reactant. Alternatively,it may be possible to use a method of continuously supplying one of theprecursor and the reactant while intermittently supplying the other.These cases can obtain the same effects as the above embodiments.

Recipes used in the substrate processing and the cleaning process may beprepared individually according to the processing contents and may bestored in the memory device 121 c via a telecommunication line or theexternal memory device 123. Moreover, at the beginning of the substrateprocessing and the cleaning process, the CPU 121 a may properly selectan appropriate recipe from the recipes stored in the memory device 121 caccording to the contents of the substrate processing and the cleaningprocess. Thus, it is possible for a single substrate processingapparatus to form films of various kinds, composition ratios, qualifies,and thicknesses with enhanced reproducibility. In addition, it ispossible to perform an appropriate cleaning process in accordance withdeposits including various films adhered in the process container(process chamber 201). Further, it is possible to reduce an operator'sburden and to quickly start the substrate processing while avoiding anoperation error.

The recipes mentioned above are not limited to newly-prepared ones burmay be prepared, for example, by modifying existing recipes that arealready installed in the substrate processing apparatus. Once therecipes are modified, the modified recipes may be installed in thesubstrate processing apparatus via a telecommunication line or arecording medium storing the recipes. In addition, the existing recipesalready installed in the substrate processing apparatus may be directlymodified by operating the input/output device 122 of the substrateprocessing apparatus.

The example in which films are formed and the inside of the processcontainer is cleaned using a batch-type substrate processing apparatuscapable of processing a plurality of substrates at a time has beendescribed in the above embodiments. The present disclosure is notlimited to the above embodiments but may be suitably applied, forexample, to a case where films are formed and the inside of the processcontainer is cleaned using a single-wafer-type substrate processingapparatus capable of processing a single substrate or several substratesat a time. In addition, the example in which films are formed and theinside of the process container is cleaned using a substrate processingapparatus provided with a hot-wall-type process furnace has beendescribed in the above embodiments. The present disclosure is notlimited to the above embodiments but may be suitably applied to a case where films are formed and the inside of the process container is cleanedusing a substrate processing apparatus provided with a cold-wall-typeprocess furnace.

In the case of using these substrate processing apparatuses, thesubstrate processing and die cleaning process may be performed accordingto the same sequence and process condition as those in the aboveembodiments and modification examples, and the same effects as those ofthe above embodiments and modification examples can be achieved.

The above embodiments, modification examples, and so on may be used inproper combination. The processing procedures and process condition usedin this case may be the same as those of the above embodiments.

Embodiment Examples

Embodiment Examples and Comparative Examples will be described belowwith reference to FIGS. 5 and 6 .

After performing substrate processing for forming SiN films over wafersusing the substrate processing apparatus shown in FIG. 14 that is, batchprocessing (BAT) for simultaneously forming SiN films over a pluralityof wafers, a predetermined number of times, as a Comparative Example, astep (F₂+NO_CLN) of removing deposits in the process container using F₂gas+NO gas and a step (After_PRG) of after-purging the inside of theprocess container were performed in this order (cleaning X). After that,after pre-coating (Pre_CT) the inside of the process container, the BATwas repeatedly performed. The execution times of After_PRG, Pre_CT, andBAT were 2 hours, 2 hours, and 4 hours, respectively. Other processcondition was the same as the process condition in each step of anEmbodiment Example to be described below.

After performing the above-mentioned BAT repeatedly after the cleaningX, as an Embodiment Example, a step (F₂+NO_CLN) of removing deposits inthe process container using F₂ gas+NO gas, a temperature increasing step(Ramp_Up), a step (N₂_cycle_PRG) of physically desorbing residualfluorine by cycle-purging the inside of the process container using alarge flow rate of N₂ gas, a step (NO_PRG) of chemically desorbing theresidual fluorine by purging the inside of the process container using aNO gas, and a step (After_PRG) of after-purging the inside of theprocess container were performed in this order (cleaning Y). After that,after pre-coating (Pre_CT) the inside of the process container, the BATwas repeatedly performed. The execution times of Ramp_Up, N₂_cycle_PRG,and NO_PRG were 0.5 hour, 1 hour, and 0.5 hour, respectively. Theexecution times of After_PRG, Pre_CT, and BAT were 2 hours, 2 hours, and4 hours, respectively, similar to the Comparative Example. Other processcondition was set as predetermined condition within the processcondition range described in the above embodiments.

After performing the cleanings X and Y, each time the above-mentionedBAT was performed, the wafer in-plane average film thickness(hereinafter, in-plane average film thickness) of SiN films formed overwafers was measured. FIG. 5 shows the measurement results of thein-plane average film thickness of the SiN films. In FIG. 5 , thehorizontal axis represents the number of times of substrate processingafter the cleanings X and Y, that is, the number of times of batchprocessing (BAT number), and the vertical axis represents the in-planeaverage film thickness (□) of the SiN films formed over the wafers. Inthe figure, white bars indicate the in-plane average film thickness ofSiN films formed over wafers disposed at the top (Top) of a waferarrangement region, and shaded bars indicate the in-plane average filmthickness of SiN films formed over wafers disposed at the bottom (Btm)of the wafer arrangement region.

As illustrated in FIG. 5 , in BAT (first to third) after the cleaning X,the in-plane average film thickness of the SiN films formed over thewafers was smaller than that of BAT (fourth or later) after that. Inaddition, the deposition rate was temporarily reduced in BAT after thecleaning process. On the other hand, in BAT after the cleaning Y, therewas no difference in the in-plane average film thickness of the SiNfilms formed over the wafers between BAT (first time) immediately afterthe cleaning Y and BAT (second time or later) after that. In addition,the temporal reduction in the deposition rate did not occur in BAT afterthe cleaning process.

As illustrated in FIG. 6 , in the Comparative Example, after F₂+NO_CLN,until substrate processing on product wafers, that is, batch processing(product BAT) for simultaneously forming SiN films over a plurality ofproduct wafers, can be started, an unstable test BAT with a smalldeposition rate had to be performed three times, which requires thedowntime of about 16 hours. On the other hand, in the EmbodimentExample, after F₂+NO_CLN, BAT performed at the first time could be astable product BAT with a large deposition rate (since a test BATbecomes unnecessary). As a result, the downtime could be suppressed toabout 6 hours. In this manner, in the Embodiment Example, it waspossible to perform the next substrate processing after cleaning theinside of the process container without deteriorating the productivityand hence to significantly shorten the downtime of the substrateprocessing apparatus.

According to the present disclosure in some embodiments, it is possibleto perform the next substrate processing without deteriorating theproductivity after cleaning the inside of a process container.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the embodiments described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the embodiments describedherein may be made without departing from the spirit of the disclosures.The accompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thedisclosures.

What is claimed is:
 1. A method of cleaning an inside of a processcontainer, comprising: (a) removing substances adhered in a processcontainer set at a first temperature after performing a process on asubstrate by supplying a first gas including a fluorine-based gas at afirst flow rate into the process container and exhausting the inside ofthe process container; (b) physically desorbing and removing residualfluorine in the process container set at a second temperature higherthan the first temperature after performing (a) by supplying a secondgas, without supplying any fluorine-based gas, at a second flow ratehigher than the first flow rate and a third flow rate into the processcontainer and exhausting the inside of the process container, the secondgas not reacting chemically with fluorine under the second temperature;and (c) chemically desorbing and removing residual fluorine in theprocess container set at a third temperature higher than the firsttemperature after performing (a) by supplying a third gas, withoutsupplying any fluorine-based gas, at the third flow rate into theprocess container and exhausting the inside of the process container,the third gas reacting chemically with fluorine under the thirdtemperature.
 2. The method according to claim 1, wherein an internalpressure of the process container in (c) is set to be higher than aninternal pressure of the process container in (b).
 3. The methodaccording to claim 1, wherein (c) is performed after performing (b). 4.The method according to claim 3, wherein (c) is performed after aninternal temperature of the process container is stabilized to the thirdtemperature.
 5. The method according to claim 1, wherein in (c),residual fluorine which has not been removed in (b) is desorbed andremoved.
 6. The method according to claim 1, wherein the secondtemperature and the third temperature are set to be equal to each other.7. The method according to claim 1, further comprising: (d) performing aprocess, which is the same as the process on the substrate, on theinside of the process container set at a fourth temperature afterperforming (c), wherein the second temperature, the third temperature,and the fourth temperature are set to be equal to one another.
 8. Themethod according to claim 1, wherein in (b), the act of supplying thesecond gas into the process container and the act of exhausting theinside of the process container are alternately repeated a plurality oftimes.
 9. The method according to claim 1, wherein the second gasincludes an inert gas, and the third gas includes a nitrogen oxide-basedgas.
 10. The method according to claim 9, wherein the first gas furtherincludes a nitrogen oxide-based gas.
 11. The method according to claim9, wherein the nitrogen oxide-based gas includes a nitrogen monoxidegas.
 12. The method according to claim 10, wherein the nitrogenoxide-based gas includes a nitrogen monoxide gas.
 13. The methodaccording to claim 1, wherein (b) and (c) are alternately repeated aplurality of times.
 14. The method according to claim 13, wherein aratio of an execution time of (c) to an execution time of (b) ischanged.
 15. The method according to claim 13, wherein a ratio of anexecution time of (c) to an execution time of (b) is graduallyincreased.
 16. The method according to claim 1, wherein (a), (b), and(c) are performed under a non-plasma atmosphere.
 17. The methodaccording to claim 1, wherein (a), (b), and (c) are performed byapplying thermal energy, without applying plasma energy, to an internalatmosphere of the process container.
 18. A method of manufacturing asemiconductor device, comprising: performing a process on a substrate ina process container; and cleaning an inside of the process container,the act of cleaning including: (a) removing substances adhered in theprocess container set at a first temperature after performing theprocess on the substrate by supplying a first gas including afluorine-based gas at a first flow rate into the process container andexhausting the inside of the process container; (b) physically desorbingand removing residual fluorine in the process container set at a secondtemperature higher than the first temperature after performing (a) bysupplying a second gas, without supplying any fluorine-based gas, at asecond flow rate higher than the first flow rate and a third flow rateinto the process container and exhausting the inside of the processcontainer, the second gas not reacting chemically with fluorine underthe second temperature; and (c) chemically desorbing and removingresidual fluorine in the process container set at a third temperaturehigher than the first temperature after performing (a) by supplying athird gas, without supplying any fluorine-based gas, at the third flowrate into the process container and exhausting the inside of the processcontainer, the third gas reacting chemically with fluorine under thethird temperature.
 19. A non-transitory computer-readable recordingmedium storing a program that causes, by a computer, a substrateprocessing apparatus to perform a process of cleaning an inside of aprocess container of the substrate processing apparatus, the processcomprising: (a) removing substances adhered in the process container setat a first temperature after performing a process on a substrate bysupplying a first gas including a fluorine-based gas at a first flowrate into the process container and exhausting the inside of the processcontainer; (b) physically desorbing and removing residual fluorine inthe process container set at a second temperature higher than the firsttemperature after performing (a) by supplying a second gas, withoutsupplying any fluorine-based gas, at a second flow rate higher than thefirst flow rate and a third flow rate into the process container andexhausting the inside of the process container, the second gas notreacting chemically with fluorine under the second temperature; and (c)chemically desorbing and removing residual fluorine in the processcontainer set at a third temperature higher than the first temperatureafter performing (a) by supplying a third gas, without supplying anyfluorine-based gas, at the third flow rate into the process containerand exhausting the inside of the process container, the third gasreacting chemically with fluorine under the third temperature.